Inkjet recording apparatuses are used in various fields since they can perform high-speed successive recording of designs or characters based on predetermined image data.
Examples of such inkjet recording apparatuses include a known inkjet recording apparatus provided with a back-pressure tank, a distribution tank, an ink on-off solenoid valve, and a recording head (for example, see Patent Literature 1 or 2).
By the way, in these inkjet recording apparatuses, since ink is supplied by making use of a water head difference between the liquid level in the back-pressure tank and the recording head, there is a certain limitation in a positional relation between the back-pressure tank and the recording head.
In addition, since a route through which ink passes from the back-pressure tank to the recording head is long, there is such a drawback that pressure loss occurs.
Further, since the pressure on ink in the recording head varies according to the liquid level in the back-pressure tank, there is the drawback that the discharge amount or discharge velocity of the ink becomes unstable.
In order to overcome these drawbacks, an inkjet recording apparatus of a pressure control type that controls pressure instead of making use of a water head difference has been developed.
For example, there is an inkjet recording apparatus provided with a main tank, a sub tank, a print head (recording head), a pressure detecting means for detecting a pressure in the sub tank, an air suction means, and an air replenishment pump (for example, see Patent Literature 3).